Extracting formula from trendline of a graph

[praveen_ce]

Hi ppl,

i am trying to extract formula(polynomial eq) frm a graph curve

say

i have two tables

10---- 50

20---- 100

30---- 150

40---- 200

50---- 250


if i plot this and extract the formula i get "y=50x"(actually "y=5x")

so it means that i have to give input as

x=1,2,3,4,5

y will give =50,100,150,200,250


What i want is


i want to give input as

x=10,20,30,40,50

i should get 50,100,150,200,250


WHEN I USE SCATTER TYPE OF GRAPH I GET PROPER FORMULA (i,e y=5x)


but to plot graph in scatter is bit tough wat i mean is if we use scatter for higher level polynomial equation trend line will be different than "LINE graph"


i hope i made myself clear

normally i am not that good at it

 

[Hui]

Praveen_ce


When you plot data on a Line chart it uses the values, 1, 2, 3, 4 ... for the X Axis values regardless of what values you specify


You should use a Scatter Chart to plot Y Values against known X Values and then the Trendline Formula will be correct


You may also want to have a read of: http://chandoo.org/wp/2011/01/27/trendlines-and-forecasting-in-excel-part-3/